Durable papers are designed to perform in environments unfriendly to regular papers, such as the generally available 100 percent fiber papers. There are four basic categories of durable papers: papers that are bulkier or in some other way stronger; papers that have been surface treated; synthetic papers; and paper/plastic laminates.
Generally, paper/plastic laminates are composed of a paper web affixed to a plastic film. These paper/plastic laminates have tear characteristics comparable to synthetic papers and surface characteristics comparable to regular paper. Beyond the tear resistance of paper/plastic laminates, the paper web can be manipulated by well known methods to give the paper surface characteristics suitable for a broad range of applications such as fine writing papers, maps or archival documents. Current paper/plastic laminates, however, suffer from an inability to be used effectively with office, midrange and high-speed traditional laser and digital copiers and digital printers, and other like equipment using heat set fuser toner adhesion as the method for fusing/bonding an ink to a paper. Current paper/plastic laminates do not work well with this equipment as the equipment employs processes during normal operation that reach temperatures at which the paper/plastic laminate loses dimensional stability, which is manifested in wrinkling and curling of the paper/plastic laminate.
The dimensional instability of current paper/plastic laminates results from the laminating method employed to bind the paper web to the plastic film. Many current laminating processes employ fluids, water or solvent, that must be removed from the laminated product by heating, or other known methods. This heating alters the characteristics of the laminate, paper web and/or plastic film, leading to the dimensional instability when the conventional equipment reheats the paper/plastic laminate. The heating process also complicates and adds cost to the manufacturing process, due to the need for additional equipment such as ovens and pollution controls, and the increased time required for manufacture.
A further problem associated with the use of fluids in manufacturing paper/plastic laminates is the limitations on the overall basis weight of the paper web. The paper web must have sufficient strength to be capable of being processed while wet. The basis weight and caliper of the paper web is, therefore, increased to assure an appropriate paper web wet strength. This leads to paper/plastic laminates that have a caliper, thus weight, greater than would otherwise have been required if fluids were not used.
A further problem associated with paper in general, and business documents in particular, is counterfeiting. Major problems have surfaced because of fraudulently produced currency, checks, election ballots, wills, legal papers, coupons, gift certificates, insurance papers, stock certificates, packaging, prescription pads and other documents is a major problem. Document fraud costs corporations, financial institutions, government agencies and individuals billions of dollars per year. Everyone therefore has the need to protect against illegal copying and adulteration of documents. In each case the security of each document depends mainly on the paper.
Current technology can provide almost anyone the tools necessary to fraudulently duplicate and manipulate paper documents. In addition to physical tampering, color copiers, personal computers and scanners are now used extensively by counterfeiters to easily duplicate original documents.
As a result various types of security papers have been developed to help mitigate the problem. Security paper is paper that has been engineered and manufactured to incorporate physical features imbedded in the paper itself to resist document forgery and the copying of original documents. The paper is fully compliant with the physical paper standards of weight, grain direction, moisture content, etc., but has additional “chemical and fiber” fraud resistant features built into the paper during the manufacturing process. The features themselves cannot be readily copied or reproduced via conventional reproduction processes.
Various techniques are used to produce security features in paper. There are “active” features, which are used to identify an original document by sight or touch and “passive” features, which become apparent when a document is photocopied or scanned. Additional action is required to activate this feature. Examples of active features are colored fibers in the paper, watermarks, optical holograms, micro printing, and security backgrounds. Passive features include invisible fluorescent fibers that can only be seen under UV backlight, words such as “void” or “unauthorized copy” appear on copy when a document is photocopied or scanned and chemically reactive paper. All of these features are intended to help prevent unauthorized document duplication and are all features that are incorporated into the paper.
Therefore, it would be beneficial if a tear-resistant paper/plastic laminate could be developed that can overcome the various known problems associated with document security.